Wonderful Ingrid left a comment asking the following question regarding ice cream:
Lindsey, I have a question…when making the custard do you remove it from the heat as soon as it hits 160 or after it hits 160, coats the back of a spoon, AND you can leave a trail?
I know this can be confusing–even if you are a seasoned custard maker.
I find that checking the temperature is more accurate than coating the back of a spoon. I add that into recipes for those who may not own an instant read thermometer.
I think there are different definitions as to what it means for the custard to “coat the back of a wooden spoon.”
Some people would let it cook longer (i.e. higher temp), others for less time.
(In the picture above, the custard is a little too thin and doesn’t quite coat the spoon–at least in my opinion.)
(In the picture above, the custard is cooked to the proper temperature and is a little thicker than the first picture.)
And also, depending on the recipe and how many egg yolks you use, it will be thicker or thinner even when it’s at the same temp. This is also true if you are using a recipe that directs you to heat the cream along with the milk (before tempering the eggs) rather than adding it later.
Mostly you just want to cook the eggs and put them into the safe zone. (Anyone else want to weigh in on this?)
So, to answer the question–
When I am making a custard for ice cream, I like to take the temperature rather than rely on it coating the back of the spoon or leaving a trail. (It is an indication that the custard has cooked if it does leave a trail and coat the spoon.)
When the temperature hits 160 degrees F. I take it off the heat immediately and strain it into a clean bowl. Then I add cold cream to bring the temp down. (You can also use an ice bath.)
If the temp goes above 160 degrees F it won’t hurt anything necessarily–unless it’s like 190 degrees or something. Then you have a curdling problem. You will even be safe up to 170-180. Some recipes I’ve seen allow for cooking it longer up to 180 degrees (about 82 degrees C). Just remember that the custard will continue to cook a little even after you’ve removed it from the heat. (This is why I like to use the method of adding cold cream to bring down the temp.)
It also depends on where you live–here in Utah the elevation is higher, so I watch even more closely because it will curdle faster here. (And it has happened to me.)
Readers, would you care to share any advice or add to (or even refute) what I’ve said?